<div id="shiny-shadow">
 <button><span>鼠标悬停</span></button>
</div>

#shiny-shadow {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  background: #1c2541;
}
button {
  border: 2px solid white;
  background: transparent;
  text-transform: uppercase;
  color: white;
  padding: 15px 50px;
  outline: none;
}
span {
  z-index: 20;
}

button {
  position: relative;
}
button:after {
    content: '';
    display: block;
    position: absolute;
    background: white;
    width: 50px;
    height: 125px;
    opacity: 20%;
}

button:after {
    transform: rotate(-45deg);
}

button:after {
    top: -2px;
    left: -1px;
}

button:hover:after {
  left: 120%;
}

button:hover:after {
  left: 120%;
  transition: all 600ms cubic-bezier(0.3, 1, 0.2, 1);
   -webkit-transition: all 600ms cubic-bezier(0.3, 1, 0.2, 1);
}

button {
  overflow: hidden;
}

button:after {
    top: -36px;
    left: -100px;
}